Amino Acid Sequence of Rat Argininosuccinate Lyase Deduced from cDNA1

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Abstract
Argininosuccinate lyase [EC 4.3.2.1] is an enzyme of the urea cycle in the liver of ureotelic animals. The enzymes of the urea cycle, including argininosuccinate lyase, are regulated developmentally and in response to dietary and hormonal changes, in a coordinated manner. The nucleotide sequence of rat argininosuccinate lyase cDNA, which was isolated previously (Amaya, Y., Kawamoto, S., Oda, T., Kuzumi, T., Saheki, T., Kimula, S., & Mori, M. (1986) Biochem. Int. 13, 433–438), was determined. The cDNA clone contained an open reading frame encoding a polypeptide of 461 amino acid residues (predicted Mr = 51,549), a 5'-untranslated sequence of 150 bp, and a 3'-untranslated sequence of 41 bp. The amino acid composition of rat liver argininosuccinate lyase predicted from the cDNA sequence is in close agreement with that determined on the purified enzyme. The predicted amino acid sequence of rat argininosuccinate lyase is homologous with the cDNA-derived amino acid sequences of the human and yeast enzymes along the entire sequences (94 and 39%, respectively), except for a region of 66 residues of the human enzyme near the COOH terminus. However, the sequence of this region of the human enzyme predicted from another reading frame of the human enzyme cDNA is homologous with the corresponding sequences of the rat and yeast enzymes. Therefore, the human sequence should be re-examined. Lysine-51, the putative binding site for argininosuccinate, and the flanking sequences are highly conserved among the rat, steer, human, and yeast enzymes.